Add more Gource captions
Add more Gource captions

This adds more captions for Gource. In particular:

* Add "Proved arch - the Archimedian Property for Reals (Norman Megill)".
  Many things were happening in 1997 but there were no comments about
  that year.  it seemed like a good idea to point out something specific
  that happened in this early year.
* Mention the Holophrasm paper (which has been mentioned many times since)
* Note OpenAI - the first machine learning based *contribution*
* Note etransc

Signed-off-by: David A. Wheeler <9ae72d22d8b894b865a7a496af4fab6320e6abb2@dwheeler.com>

metamath/set.mm,metamath/set.mm,metamath/set.mm